Low or missing ______________ is an indication that the problem is not the SSR

• A. line voltage
• B. load current
• C. control signal
• D. ambient temperature

Answer: (A)

The important idea here is diagnosing SSRs by looking at the control input. An SSR has a low-voltage control side and a high-power load side. If the control signal is low or missing, the SSR will not switch at all, regardless of the condition of its output. That tells you the fault lies in the control circuitry or wiring feeding the SSR, not in the SSR’s switching element itself.

This is why a low or absent control signal is the best indicator that the problem isn’t with the SSR. Other factors like line voltage, ambient temperature, or load current can affect performance, but they don’t directly show that the SSR itself is fine and that the control side is the issue.